Abstract: On the basis of the data collected from observation in six consecutive years water balance and evapotranspiration were studied. The results indicate that precipitation is 1065.5mm/year in the small watershed; that the crown-interception is 264.6mm/year, i.e. 24.8% of the total precipitation; that precipitation through crown is 799.82mm/year, i.e. 75.1% of the precipitation; that water stemflow is 1.08mm/year, about 0.1% of the precipitation; that water output in the form of runoff is 212.27mm/year of which the ground water is 203.00mm/year and surface runoff is only 9.27mm/year, thus total runoff coefficient is 0.199. On consecutive measurements of 6 years. The monthly change of soil moisture is great, but the change between years is only ±12.80, which is 1.2% of precipitation in the output of water from the ecosystem,evapotranspiration is greatest (866.03mm/year), which is 81.3% of precipitation. Of this amount,the evaporation crown-intercept is 264.6mm/year,about 31.6% of total evapotranspiration.